The invention relates generally to data storage devices that use removable cartridges and, more particularly, to a system for properly positioning a removable data storage cartridge in a read/write mechanism.
A widely used medium for storing data is recording tape, which is typically a polymer tape with a magnetic coating. Tape cartridges are one of the most popular formats for storing data on tape. Tape cartridges are usually smaller and less expensive than reel-to-reel tapes. Two widely used types of tape cartridges are the dual reel cartridge and the single supply reel cartridge. By enclosing the tape within a cartridge, the tape and the data stored on the tape are better protected from damage than the more exposed reel-to-reel tapes. In a dual reel tape cartridge, both the supply reel and the take-up reel are housed in the cartridge. In a single supply reel tape cartridge, the take-up reel is built into the tape drive along with an automatic tape threading mechanism.
In many tape cartridge drive systems, the tape cartridges are carried into the proper position in the tape drive on a tray that moves in and out of the tape drive. The tray moves back and forth between an extended/loading position for receiving a tape cartridge and a retracted/operating position in the drive for positioning the cartridge for read and write operations. A paired hole/slot positioning system is commonly used to accurately position the cartridge in the tape drive as the cartridge is loaded. In this system, a hole and a slot are formed in the bottom of the cartridge along a line parallel to the vertical plane of the front of the cartridge. As the tray moves to the retracted position, it carries the cartridge in and down over a pair of alignment pins affixed to the tape drive. One of the alignment pins projects into the hole in the bottom of the cartridge. The other alignment pin projects into the slot. The hole/slot pair on the cartridge and the alignment pins on the tape drive are located such that when the pins project into the hole and slot, the cartridge and corresponding the tape within the cartridge, will be properly positioned in the tape drive.
In order to accommodate some initial misalignment between the hole and slot and the alignment pins, the edges of the hole and slot are chamfered or the ends of the pins are chamfered, or both. In this way, if the cartridge is not precisely aligned as it drops down over the pins, the beveled edges of the chamfers will move the cartridge into the proper position to receive the alignment pins. The size of the hole/slot and pins and their chamfered edges determines how much misalignment can be accommodated and how much vertical travel is required to get the pins into the hole and slot. Making the hole, slot and pins and their chamfers larger, and increasing the vertical travel, increases the allowable misalignment. It is desirable, however, to minimize or eliminate the vertical travel necessary to properly position the cartridge in the tape drive and to keep the hole, slot and pins and the chamfers as small as possible because all of these factors add cost and complexity to the tape cartridge and the tape drive.
Accordingly, the present invention is directed to a system for positioning a data storage cartridge in a read/write mechanism in which alignment holes in the cartridge are pre-aligned to alignment structures on the read/write mechanism. The cartridge may be characterized by a first planar surface that fronts the tape drive and a second planar surface perpendicular to and extending away from the first planar surface. The cartridge is movable in a first direction from a loading position to a pre-aligned position in which the cartridge is partially installed in the read/write mechanism and then in a second direction transverse to the first direction from the pre-aligned position to an aligned operating position in which the cartridge is fully installed in the read/write mechanism.
The invented system includes a beveled recess in the first planar surface of the cartridge, a pair of holes in the second planar surface of the cartridge and four alignment structures affixed to the read/write mechanism (first, second, third and fourth alignment structures). The third and fourth alignment structures, typically pins, are oriented perpendicular to and project out toward the second planar surface of the cartridge. The first alignment structure is disposed in the read/write mechanism such that as the cartridge is moved toward the pre-aligned position the first alignment structure abuts the beveled recess. The first, second, third and fourth alignment structures are disposed such that when the cartridge reaches the pre-aligned position the first alignment structure bottoms out in the beveled recess, the second alignment structure abuts the first planar surface at a location away from the beveled recess, the third alignment structure is substantially aligned with one of the holes in the second planar surface and the fourth alignment structure is substantially aligned with the other of the holes in the second planar surface. One or both of the alignment holes on the cartridge and the alignment pins on the read/write mechanism may be chamfered to accommodate any misalignment between the holes and the pins.
The invention may also be embodied in a housing for the cartridge. In this embodiment, the cartridge housing includes a top, a bottom, and a front and sides connecting the top and bottom. A beveled recess is formed in the front of the housing and a flat surface is located on the front of the housing at a position away from the beveled recess. A pair of alignment holes are positioned in the bottom of the housing, preferably along a line parallel to the flat surface on the front of the housing. The beveled recess, flat surface and alignment holes are used in conjunction with alignment structures in the read/write mechanism, as described above for the system embodiment of the invention, to properly align the cartridge when it is installed in the read/write mechanism.
The pre-alignment features of the invention reduce the vertical travel necessary to properly position the data storage cartridge (a tape cartridge, for example) in the read/write mechanism (a tape drive, for example) and to keep the alignment holes on the cartridge and the alignment pins on the read/write mechanism and the chamfers as small as possible.
The various embodiments of the invention may be better understood with reference to the Drawings and the following Detailed Description.